Signaling system



Nov. 12, 1946. F. c. EVANS 1 Y SIGNALING SYSTEM Filed Dec. 16', 1941 4 Sheets-Sheet 1 FIIG.I

TO CENTRAL STATION TO OTHER TRANSMITTERS BY y. {M

ATTORNEY Nov. 12, 1946. F. c. EVANS SIGNALING SYSTEM Filed Dec. 16, 1941 4 Sheets-Sheet 2 'FIG.4

INVENTOR I F. c. EVANS ATTORNEY Nov. 12, 1946.

F. c. EVANS 2,410,814

SIGNALING SYSTEM Fiied Dec. 16, 1941 4 Sheets-Sheet s INVENTOR F? C. EVANS ATTORNEY Nov. 12, 1946. F. c. EVANS 2,410,814

SIGNALING SYSTEM Filed Dec 16, 1941 4 Sheets-Sheet 4 INVENTOR F. C. EVANS ATTORNEY Patented Nov. 12, 1946 SIGNALING SYSTEM Francis G. Evans, Dongan Hills, N. Y., assignor to American District Telegraph Company, Jersey City, N. J., a corporation of New Jersey Application December 16, 1941, Serial No. 423,130

Claims. 1

This invention relates generally to signaling systems and more particularly to aero tube alarm systems for detecting dangerous rises of temperature and initiating an alarm signal in response thereto.

Aero tube alarm systems consist of one or more lengths of aero tubing extending through and about an enclosure which it is desired to protect and in such relation to the enclosure that'dangerous temperatures can be detected within a minimum time. The tubing may contain a gas either under, at or in excess of atmospheric pressure, which gas expands in response to increases of temperature to thereby increase the pressure within the system. In accordance with conventional practice each end of the tubing circuit is connected to an expansion chamber consisting of a pair of flexible diaphragms for converting changes of pressure within the tubing system into mechanical motion which may be utilized to operate electrical contacts. The tubing system may be operated to respond to a predetermined temperature or a predetermined rate of rise of temperature, the latter characteristic being obtained by the provision of a, vent adjacent each expansion chamber for compensating pressure changes occurring at a rate below fixed limit-s whereby normal temperature changes do not result in the initiation of an alarm. If, however, a dangerous rate of change of temperature occurs, the expansion of the gas within the tubing system occurs at such a high rate that the pressure within the expansion chamber exceeds the limiting pressure to thereby initiate an alarm.

It has been the practice to operate electrical contacts by means of the pressure responsive diaphragms to thereby change the characteristics of an electrical circuit and in turn initiate operation of a signal transmitter by means of an electro-mechanically operated trip mechanism. The trip mechanism releases an electrical signal transmitting device to cause transmission of code signal impulses from the transmitter located in the protected premises, over a transmission line to a central station to thereby summon assistance. The use of electrical circuits including contacts and electro-mechanical devices in the protected premises necessitates the use of local battery sources of electrical energy, thereby increasing the expense of installation and the amount of investment required in the alarm system.

The alarm signal transmitter, which is electrically tripped, is usually driven by a spring motor which requires manual winding after each alarm transmitting operation, and it is necessary that the condition of the spring driven motor be known to the central station attendant. Therefore, such transmitters are adapted to transmit a restoration signal after each winding operation which signal indicates to the central station attendant that the transmitter has been wound and is in condition to respond to the fire detecting system and transmit an alarm signal. It is necessary, however, to insure that the transmitter is wound to such an extent that the restoration signal will be automatically transmitted as it frequently happens that unskilled persons reset and wind the transmitter, and it is further necessary that such transmitters be provided with mechanism for preventing a saboteur' or incendiary from blocking the action of a transmitter to thereby accomplish his purpose without the initiation of a. fire alarm.

The principal object of this invention is to provide a signal transmitter which may be directly and mechanically operated by and in response to small temperature-induced pressure variations in an aero tubesystem.

A further object of this invention is to provide a mechanically tripped signal transmitter for use in aero tube fire alarm systems which is sensitive to low pressure variations in such systems and at the same time resistant to the efiects of vibration.

A further object of this invention is to provide a mechanical trip mechanism in a signaltransmitter which is responsive to pressure changes within .an aero tube circuit in a positive and foolproof manner.

A still further object of this invention is to provide an aero tube fire alarm system including a mechanically tripped signal transmitter, the system having uniform sensitivity to temperature changes of a predetermined rate of rise throughout its entire length.

Still anotherobject of this invention is to providean aero tube system which may include pressure detecting diaphragms having non-similar characteristics, together with a means for obtaining uniform operation and sensitivity throughout the system in spite of the said non-uniform characteristics.

Further objects and advantages of this system will be apparent after consideration of the fol-, lowing specification and the accompanying drawings wherein:

Fig. 1 diagrammatically illustrates two aero tube fire detecting systems, together with signal transmitters Fig. 2 is a front elevation of the signal transmitter embodying this invention;

Fig. 3 is a front of Fig. 2 with the front plate removed;

Fig. 4 is a, view from the right side of Fig. 2;

Fig. 5 is a view from the left side of Fig. 2;

Fig. 6 is an expanded perspective of the transmitter with supporting structure omitted;

Figs. 6a, 6b, and 6c are fragmentary view of a portion of the key winding mechanism shown in Fig. 6;

Fig. 7 illustrates the spring motor trip mechanism in its rundown condition;

Fig. 8 illustrates the spring motor trip mechanism after 120 degrees of rotation during the winding operation;

Fig. 9 illustrates the spring motor trip mechanism after 240 degrees of rotation during the winding operation;

Fig. 10 illustrates the spring motor trip mechanism after 360 degrees of rotation during the winding operation;

Fig. 11 illustrates the spring motor trip mechanism at the start of transmission of the restoration signal;

Fig. 12 shows the spring motor trip mechanism in condition to transmit an alarm signal;

Fig. 13 illustrates the diaphragm operated trip mechanism in the running condition; and

Fig. 14 illustrates the diaphragm operated trip mechanism in a position preparatory to transmission of an alarm signal.

Fig. 1 of the drawings illustrates a pair of separate aero tube circuits l and 3, each of which may individually be located within separate enclosures such as one or more rooms in separate buildings or groups of rooms in the same buildin for the purpose of detecting dangerous rises of temperature therein. Each of the circuits l and 3 is connected to the transmitters 2 and 4, respectively, these transmitters being connected as shown in Fig. 1 in a loop circuit which terminates at a central station Where annunciators, recorders and alarm devices are arranged to be responsive to transmitted signals. Fig. 1 is an illustration by way of example only, it being intended that the system shall include whatever number of aero tube circuits and transmitters may be necessary and feasible in a particular installation.

The tubing circuits terminate at each transmitter in detector units such as are partially shown in Figs. 2 and 3 of the drawings, and which may be constructed in accordance with the'specificatio-n and drawings of the patent to F. M. Cowan, No. 2,100,184, of November 23, 1937. Fig. 2 of the drawings shows tubing 8 entering the detector unit designated in general by numeral 10, this unit containing passages from each end of the tubing to the diaphragm expansion devices l2. Diaphragms [2 are connected together, as shown in Fig. 3, to act either separately or in unison by means of the arm l4 and links l5 so that the operative function of the aero tube system as a whole occurs at the midpoint of arm M which is the V-shaped portion it. This overcomes the characteristic of non-uniform response in aero tube systems which is caused by different degrees of response, depending upon the proximity of a fire condition to one or the other of the diaphragms i2 at the ends of the tube. Thus, the degree of displacement varies in accordance with the proximity of the fire to each diaphragm. However, it will be seen that the degree of movement at the point I6 on arm l4 will be the same regardless of the degree of movement of each of the diaphragms [2. For instance, a fire in the vicinity of the point 5 in tubing circuit 1 will expand the air within the tubing and cause defiection of diaphragm I2 connected to the near end of the tubing circuit but will cause very I slight, if any, deflection of the diaphragm connected to the other end of the tubing circuit. Therefore, one end of the arm [4 will be lowered about the other end of the arm as the pivot point, the point I6 moving one-half the distance through which the actuated end can move. Thus, a fire at either end of the tubing circuit causes a deflection at point l6 equal to one-half the deflection of the actuated diaphragm. If a fire occurs at a point equidistant from the ends of the loop, both of the diaphragms l2 are deflected only one-half as much as each of them would be if the fire was located close thereto, but both of the diaphragms are deflected to thereby cause the point l6 of arm l4 to move through the same distance as it does when only one diaphragm is deflected.

This characteristic of the system constructed in accordance with this invention eliminates the necessity for adjusting a trip element or contact elements for any particular maximum or minimum degree of movement of the diaphragms for the reason that regardless of the location of the fire with respect to the ends of the loop circuit the point It of arm l4 always travels through the same distance. Furthermore, this feature of the invention averages whatever diiierences there may be in the characteristics of different diaphragms so that the aero tube circuit is uniformly sensitive throughout its length and the motion of the point l6 of arm i4 is approximately the same regardless of slight variations in the degree of deflection of said different diaphragms under the same pressure conditions.

The effects of vibration on the tripping mechanism are eliminated by the provision of weight I! in slot 41 of lever Q0. The Weight I1 is adjustable horizontally in slot 41 to vary the downward tension on diaphragms l2 to thereby adjust the point on the performance curves of both of the diaphragms at which they start to deflect in response to pressure impulses from the tubing circuit. The sensitivity of the aero tube circuit is therefore definitely determinable and improved. Weight I! also deflects diaphragms l2 to such an extent that lever 40 is positively retained at its lower limit of travel except when the pressure within the tubing changes this level by deflecting the diaphragms. Since the position of lever 40 is normally fixed by the efiects of weight l1, vibration of the transmitter cannot cause it to trip, the reason for this being that the right hand end of lever 40 must move downwardly to trip the fan 36 but this movement is prevented since diaphragms l2 are normally positioned by weight l! to fix the lower limit of travel of this end of the arm 40. Thus the only effects of vibration are to cause upward movement of the right hand end of arm 49 and downward movement of hook 42 which is in fact a movement in the latching direction with respect to fan 36. Therefore, the provision of weight I1 overcomes an outstanding defect in mechanically tripped transmitters in that false operation caused by mechanical vibration is completely eliminated.

The system constructed in accordance with this invention is particularly adapted for use in connection with mechanically tripped impulse transmitters such as that shown in Figs. 2 to 14 of the drawings. Fig. 3 of the drawings illustrates in general the source of power for the transmitter together with the trip mechanism which is connected to the point [6 of arm M for releasing the power source upon the occurrence of a predetermined rate-of-rise of temperature within the protected enclosure. The source of power in this particular illustration of the impulse transmitter is a spring motor which is most clearly shown in Figs. .4 and 6 of the drawings and comprises a pair of coiled leaf springs and 2| anchored in any suitable fashion to the drive shaft 23 supported in frames l3 and I9. Two springs are provided for insuring against the possible loss of a source of power in the event that one spring should fail. The motordrives shafts 24, 26, 28 and 36, also supported in frames l8 and I9, through a gear train comprising gears 25, 21, 29, 3| and pinions 32, 3 3, 34 and 35, whereby the motion of shaft 23 is multiplied to such a speed as to rotate the shaft 3|] at whatever speed is most suitable. Fan 36 which acts as a governing device and a control device is normally prevented from rotating by means of the lever or detent 46 having a hook portion 42 for engagement with a portion of the fan 36. Lever 46 is pivoted on the adjustable pivots 44 and connected to point N5 of arm M by means of a perpendicular arm 39. The lever is pivoted along its length atsuch a point that hook 42 moves through a distance equal to the deflection of either of diaphragms |2 whereby its entire motion is useful at the tripping point.

It is necessary that the degree of engagement between hook 42 and fan 36 be adjustable and, therefore, the pivots 44, supported in the yoke 46, and also lugs 48 extending from yoke 46 are held in alignment vertically in the slots 49 in frames I8 and I9 shown in Fig. 2 of the drawings. The pivots 44 are positioned vertically by an adjustment assembly comprising springs 56, a screw 5| and a nut 52 which moves horizontally and engages a lever 53 pivotally attached thereto and at its upper end to the yoke 46 whereby rotation of screw 5| controls the elevation of yoke 46 together with the degree of engagement between fan 36 and hook 42. The yoke 46 is biased downwardly by a pair of springs to provide proper positioning of the entire assembly.

The trip lever 40 is arranged to be deflected in a horizontal plane as well as a vertical plane for the purpose of providing a manual release for initiating fire alarms manually. Fan 36 is provided with a slot '31 whereby deflection of lever 43 in a horizontal direction may break the engagement between hook 42 and fan 36 and allow the mechanism to operate even though the aero tube circuit has not operated. The Wide slot 38 in fan 36 permits rotation regardless of the position of hook 42 provided that hook 42 is in alignment with slot 31. Lever 40 is pivoted for motion in a horizontal plane by means of a pivot member 4| extending through the block 45 which is the support for lever 40 pivoted on the pivot screws 44. As illustrated, the lever 40 includes the bent over portions 43 which engage pivot pin 4| to allow motion in a horizontal plane as well as a vertical plane. It is to be understood that any suitable pivot arrangement for obtaining motion vertically and horizontally may be used.

The manual trip mechanism includes lever pivoted at 63, as shown in Figs. 2 and 6, and connected with fan 36 by means of a slotted lever 65, the slot 66 therein providing engagement with the lever 40 to impart horizontal motion thereto. The operating arm 63 is attached to lever 60 and when operated by manual pressure, forces arm 40 through lever to swing the hook 42 into slot 3! of fan 36 to allow the mechanism to operate.

6 Leaf spring 64 acts to force the lever 60 and consequently hook 42 forwardly to normal fan-locking position.

It is necessary that the manual trip mechanism (and particularly lever 60) be controlled by the motor winding mechanism to the extent that this lever, after the transmission of alarm signals, remains in a position causing hook 42 to be out of the path of fan 36, so that when the springs are rewound and then released to unwind, a restoration signal is automatically transmitted. This operation is desirable since alarm transmitters transmit alarm signals and are then in a rundown condition which requires restoration to the normal condition for again transmitting a subsequent alarm. It is further necessary that the central office attendant be informed of the fact that the alarm system has been restored to its normal condition, and, therefore the hereinbefore described trip mechanism must be controlled during the winding operation and the transmission of restoration signals to start and stop the transmitter at the beginning and end of the restoration signals.

The main shaft 23 of the spring motor has fixed thereon a ratchet wheel 10. The pawl 1|, which engages with the notches in ratchet wheel '10, is pinned on gear 25, as illustrated in the drawings. Gear 25 floats on shaft 23 and is normally locked against rotation as will be explained subsequently, and thus, when the shaft 23 is rotated by the key, springs 20 and 2| are tightened to fully wound condition and held there by pawl 1| in engagement with ratchet 19. Shaft 23 also rotates cam member l5 which is fixed thereto. Cam 15 includes slot 62, the leading edge of which is perpendicular to the vertical surface of the cam so that the pin 6| in lever arm 60 can drop suddenly into slot 62 to thereby provide a positive stopping motion of arm 65 and hook 42 of the tripping mechanism. The other edge of slot 62 is beveled to lift the pin 6|. Secondary cam 14 floats on shaft 23 and is provided with slot 13 which extends through an arc of several degrees with respect to the center of cam 14. Pin 11 in cam I5 extends through slot 13 and moves freely therein for several degrees of rotation of cam 15 so that there is lost motion between cam 15 and the secondary cam 14. Thus, when the shaft 23 rotates through the winding cycle, cams 14 and 15 are also rotated.

Cam 14 supports and moves pin 18 in operative relation with the arm of stop lever 19 which is rotatably pinned to frame I8. Stop lever I9 also includes the projecting lug 8| which engages with a pin 82 on wheel 25 to prevent rotation of wheel 25 during the winding cycle. Arm 84 of-member 19 engages the manual trip lever 66 to perform the same function as that which occurs when lever 50 is manually operated. Thus, during .the winding cycle, lever arm 63 is held in a nontripping position until pin 76 engages arm 80 to rotate member 19 in a counter-clockwise direction, at which time arm 8| disengages from pin 82 and arm 84 disengages from lever 60. Lever I9 is held in either of its two positions by spring 83 in engagement with lug 85. The operation of the drive shaft assembly will be described in more detail later on in the description.

Transmission of impulses is provided by impulse wheel H0 which rotates with shaft 24, driven from gear 25 through pinion 32. Impulse wheel H0 engages the contact springs i so that the teeth of wheel I I0 intermittently open springs II! to cause intermittent making and breaking of the transmission circuit and consequent transmission of the code signals.

The winding mechanism is provided with a key trapping device consisting of a yoke 90 on frame I8 having a keyhole 92 which is so shaped and proportioned that key I00, the handle of which has been omitted from the drawings, and the pin IOI of the key I can be engaged with slot I02 in hub I6 on shaft 23 for commencing the winding operation. The keyhole is so proportioned, however, that as soon as the winding operation starts, with key I00 rotated in a clockwise direction, pin IOI rotates behind the yoke 90, which thereby prevents withdrawal of the key for a certain portion of the winding cycle. While the key can be rotated counterclockwise and then removed after a short are of winding movement, once the pawl H engages a notch in wheel I0 to hold the spring motor partially wound, such counterclockwise movement as would permit withdrawal of the key is prevented. The key trapping mechanism also includes a bent lever I05 which is pivoted to yoke 90 on pin 93 and influenced by spring I06 on yoke 90 in a direction toward the cam 75. However, as the key I00 is rotated, its pin |0I engages yoke 90 and then the rear side of member I05 until rotated to such a point that the transmission of a restoration signal will be assured. Lever I05 prevents extraction of the key since it is of such a length that it extends beyond the keyhole in yoke 90 whereby key I00 must be rotated until clear of the lever. It should be noticed that Fig. 11 of the drawings (wherein the illustrated parts are similar to those of Fig. 12 in which reference characters are applied) shows the cam I5 and the associated elements in such a position that pawl II is out of engagement with ratchet I0 whereby key member IOI may rotate past the end of member I05 at which time this member is forced back against the cam I5. Pin IOI may then engage the outer surface of that member so that, as shaft 23 rotates in a counter-clockwise direction under the influence of springs 20 and 2 I, key I00 will be forced out of engagement with shaft 23.

Since the drawings illustrate in Figs. 2, 4, 5, 6 and '7 the transmitter in its rundown condition, the operation will be described starting with the winding operation. When key I00 is inserted in hub I6 of cam I5, pin IOI on the key engages in a slot I02 in hub I6. The key is rotated in a clockwise direction through 120 or until pawl II on main gear 25 engages in the first notch of ratchet I0 as shown in Fig. 8. After the pawl has engaged the first notch of ratchet I0 it is impossible to withdraw the key I00 since it is looked against withdrawal by virtue of the fact that the pin IOI has passed underneath a portion of the yoke 90 of the keytrap and thus it will be necessary to continue the clockwise rotation of the key and the winding operation before the key can be removed. Another 120 of rotation of the key engages pawl II with a second notch in ratchet I0, as shown in Fig. 9, the spring motor becoming more tightly wound. In the meantime cam I5 is rotated and in so doing has turned the secondary cam I I by means of pin II which engages in the slot I3 in cam I4. Therefore secondary cam I4 is no longer holding the stop lever I9 in the stopped 01' rundown position but the stop lever still cannot move as spring 83 is holding it in place by engaging lug 85.

8 this pin will be prevented from falling into the notch by reason of the engagement of arm 84 of stop lever I9 with the end of operating arm 60, the reason for this arrangement being the fact that the edge of notch 62 which would contact the pin 6| during the winding operation is verv tical as is the surface of the pin that would contact the edge. The reason for the vertical edges is to provide a positive stop by suddenly moving lever 60, arm 65 and hook 42 in engagement with fan 36, after the transmission of the restoration signal, but if these two vertical surfaces were permitted to meet during the winding operation, it would be impossible to wind the mechanism beyond that point. Considering that the key has now been rotated through 360, it is still impossible to withdraw the key for the reason that the pin IOI has passed under lever I05, this lever rotating about its pivot point against spring I06 to permit rotation of the key. It is to be noted that lever I05 is long enough to engage a portion of yoke 90 thereby preventing rotation beyond the plane of yoke 90, whereby key I00 is trapped in its winding position. Therefore the key must be turned through an additional 30 as shown in Fig. 11, before pin IOI becomes disengaged from lever I05. After 30 return motion key I00 may be removed owing to the fact that lever I05 is beveled at its free end, as illustrated at I0I. As this additional winding is done, the pin 11 in main cam I5 takes up the slack in slot I3 in cam I4 and pulls it through a sufficient angle so that pin I8 of cam I4 engages arm of stop lever I9 and rotates the stop lever through a small angle in a counter-clockwise direction, thus having the cam surface past the bent portion of spring 83 where it is held as shown in Fig. 11 until forcibly restored to the position shown in Fig. 6. When stop lever I9 rotates in a counter-clockwise direction, arm 84 rises above operating arm 60, allowing pin 6I to rest against the surface of cam I5, and the arm 0| of stop lever I9 is disengaged from pin 82 on gear 25 so that the spring motor is free to drive the mechanism. As the mechanism runs after being released in the above manner, code wheel H0 is rotated in the obvious manner through one round of signals which designate the restoration operation and cam I5 rotates in a counter-clockwise direction until notch 62 engages pin 6I as shown in Fig. 12, whereupon operating arm 60 moves about its pivot point 63 under the influence of spring 64, the pin BI engaging the vertical surface of notch 62 in cam I5 to stop the mechanism. The transmitter is now in its normal or rest position and ready to be tripped for sending an alarm.

It should be noted that during the return motion of the mechanism, pin IOI of key I00 is disengaged from slot I02 owing to the fact that pin I 0| engages the outer sloping surface of lever I05 which surface forces the key free of slot I02 to thereby prevent defeat of the transmitter such as willful application of force through the key to prevent rotation of the mechanism and transmission of an alarm.

The vertical surfaces on pin GI and slot 62 of cam I5 are of particular significance since if these surfaces were round or sloped, the motion of operating lever 60 would be slow and the entire mechanism would stop as soon as lever 65 pulled lever 40 to the right far enough to engage a portion of fan 36. This would occur considerably before pin 6| could be fully engaged with slot 62 and under this condition a fire in the protected premises could develop a pressure in the diaphragms I 2 and hook 4 2 would operate satisfactorily, but-the first operation of the mechanism would carry arms 60 and 65 further to the right and further into engagement position, and if the pressure did not last sufiiciently long or if there was slight rotary motion due to some parts not being in exact alignment, the mechanism might 'stop because thehook 42 would engage the fan 36. However, the vertical edges on pin 6! and notch 62 permit lever 68 to assume its normal position very rapidly and thus hook 42 is moved into full engagement with fan 36 within one revolution thereof. Consequently when a fire occurs and diaphragms l2 operate, fan 36 is released and with every turn of the mechanism, levers 60 and 65 will move further and further to the left and full disengagement position under the influence of pin BI and arm 60. h The sequence of operations described hereinbefore ends with rotation of code wheel I it which occurs as the result of release of the driving motor at the end of the winding cycle. The teeth on code wheel H act on contact springs HI to transmit a one round restoration signal through the central oifice for the purpose of indicating that the transmitter has been wound and restored to normal condition and is therefore prepared for transmission of an alarm signal.

The aero tube system illustrated by way of eX- ample in Fig. 1 normally consists of several circuits, each of which extends through a protected area for supervising temperature changes and detecting fire conditions within that area. If a fire should occur near one end of the circuit, pressure very little if at all at the other end, this being due to the well known capillary characteristics of aero tubing which cause transmission of pressure pulses through the tubing. abovecondition, the pressure builds up in the left diaphragm, this particular diaphragm being taken by way of example for purposes of illustration. This diaphragm under the influence of increasing pressure moves downwardly and lowers one end of the crossbar M, the other diaphragm remaining stationary and serving as a pivot for the operated end of the bar M. The'central portion of crossbar M will descend only one-half as far-as the active end-of the crossbar for obvious reasons. Thus lever 40 pivots about pivots 44, the end 39 attached to crossbar i4 moving downwardlyand the opposite end to which hook 42 is attached moving upwardly. Hook 42 moves a dis tance equal to the expansion of the diaphragm =1 since that end of arm 40 is twiceas long as the other end. When suflicient pressure and expansion of diaphragm l 2 occurs, hook 42 is raised out of engagement with fan 36 thereby allowing the mechanism to start under the influence of the drive springs 20 and 2!. When the mechanism starts, the pin 6! is lifted out of notch 62 in cam 15, thereby rotating operating arm 60 about its pivot 63 so that the notchedarm 65 pushes lever 40 to the left whereby the hook 42 is in line with the slot in fan 36. Thus if the pressure in the operated diaphragm i 2 decreases for some reason, for instance, because of destruction of a. portion of the aero tube circuit by fire, the mechanism cannot be stopped from running since, hook 42 is not only raised above fan 36 but is in alignment with the slot 31. a

If the fire occurs in the center of the aero tube circuit, that is, at a point equidistant between its ends, pressure is developed and rises equally throughout the tube circuit so that both dia-' 1n the tubing will increase greatly at that end and Assuming the phragms expand substantially simultaneously and at the same rate. Under these circumstances the pressure is distributed between the twodiaphragms and therefore the deflection of each one is only one-half as great as it would be in the case of a similar fire condition at one end of the circuit. Crossbar I4. is lowered at both ends but only through one-half the distance at each end in comparison to the previously outlined situation Where only one diaphragm could expand. Even so, the center of crossbar It moves the same distance that it would when the fire is at either end of the circuit, and therefore hook 42 of arm 40 moves through the same distance regardless of thelocation of the fire with respect to the aero tube 'circuit, and thus the center of the circuit is exactly as sensitive to a fire condition as theends of that;circuit. This characteristic of the tripping unit 12, l5, I4, .39, 40, 42 permits adjustment offthe system toobtain sufiicient sensitivity to a fire at the center of the circuit without rendering the.system oversensitive to unusual heat conditions which may exist at the ends of the circuit and whichdetermine the extent of sensitivity adjustment; The above described action of crossarm 14 and lever is the -same for fires onequarter-of the way along the circuit or threequartersof the way along-the circuit, or at any other point in the circuit except that bothdiaphragms will expand a proportional amount and the net movement at the center of the cross-arm I4 will bethe same regardlessof the location of thefire with respect to the circuit.

When thetransmitter is started, impulse Wheel IIU rotates through fivecomplete revolutions, thereby sending a five. round signal by operating contact springs l H which are connected to the transmission line.. Cams M and 15 rotate counterclockwise' from the normal fully wound position shown in Fig, v12 through approximately i3'30 until'pin I8 and cam 14 engages arm 80 on stop lever 19, at. which time stop lever 19 rotates in a-clockwise direction to move the projection 85 to the right of the-bent portion of spring 83 i5 and bent. arm 8| rotates into the way of pin 82 in main gear 25, thereby stopping the spring motor. At this time cam 75 opens the shunt springs I [-6, since the cutaway portion of thecam allows 1;; these springs to open. The transmitter is now in the run-down condition and requires winding,

as described hereinbefore. i Provision is made for manual operation of the transmitter inthat horizontal pressure. on lug 68 of arm-60 moves the lever! through the slottedlink 65 so that hook 42 of arm 40 enters slot 31 .andis disengaged from .fan 36.' Thus the transmitter is againreleased to operate in the manner described above in connection with ini tiation of an-alarm by the aero tube system. Any form of manually operated push button or lever is suitable for manually-initiatin analarm but Fig. 4 illustrates by way of example only a breakglass spring-operated rotatable lever at I20, such as that shown in Patent No. 1,434,096, granted October 31,1922, When the glass is broken, the spring isreleased to. exert pressure on arm 68 of leverBO, whereupon pin 6| is forced out of the slot 62 after which further pressure is unnecessary since operating arm 60 is maintained in the 70 operated position by the surface of cam 1-5 pressingonpin6l. a

The release mechanism shown iii-Figs. 3, 4, 5 and 6 isadjustable by' means of the screw 5| which, when rotated, forces the nut 52 in a hori- Zontal direction thereby lifting the yoke 45 through link 53 or lowering it, depending upon the direction of rotation of screw Clockwise rotation of screw 5| raises yoke 46 to decrease the pressure required to release the mechanism, since the end of lever arm 40 is also raised. Rotation of the screw in the opposite direction lowers yoke 46 and thereby increases the pressure necessary to effect release of the mechanism.

The two contacts mounted on the same support as the spring 64 are utilized for the purpose of actuating a local alarm or for any other desired purpose such as activating relays controlling a power source and the like when the transmitter is operated to transmit a signal. By reference to Fig. 6 it will be seen that the outermost long contact of this pair has a spacer engaging the upper end of the spring 64 and when this spring 64 is in its most forward position, the contacts are held open. However, when spring 64 is moved to the rear by movement of lever 60, the outer long contact of the pair follows such movement closing the two contact points and thereby permitting the closing of such local circuit as may be provided. The two contacts H6 are used in the normal manner to short out any other transmitter following this particular transmitter in the customary loop circuit so that such latter transmitter cannot operate during the running of this transmitter.

It is to be noted that the aero tube system has increased sensitivity because the diaphragms are stressed a predetermined amount by means of the weight I1 whereby a downward force is exerted on the end of arm 40 which is attached to the cross-arm M. The weight provides a fairly heavy gravitational force to perform the actual work of operating the detent when the diaphragms are expanded whereby instead of relying entirely upon the aero tube pressure and the diaphragm as the sole source of power, they merely permit the gravitational force exerted by weight I! to take effect on arm 40 as the pressure increases in the aero tubing circuit. Weight 11 also loads or biases the diaphragms l2 so that they actually start operating at a point on the straight line portion of their expansion curves so that their action is more accurately predictable and greater movement per ounce of pressure increase is obtained. A further important advantage of the function of weight I! is the fact that lever arm 40 is loaded in the direction in which it operates, and it is free to move in the holding direction whereby vibration does not cause accidental release, change of adjustment, or jamming of the mechanism. This feature of the invention makes a mechanically tripped transmitter practical and fool-proof. Furthermore, a series of releases by vibration would have to occur before the transmitter could be accidentally tripped since, as is plainly evident, th fan 36 must go through a number of revolutions before cam 15 can have moved sufficiently to disengage pin 6| from slot 62 to effect actual complete release of the mechanism,

From the above description it is also evident that another important feature of this invention is the arrangement of the cross-arm M for providing a tripping motion which is always uniform in length regardless of the location of the fire with respect to th ends of the aero tube circuit, whereby equal sensitivity of all parts of the circuit is obtained.

A still further important feature of this invention is the provision of th key-trapping mechanism including yoke and arm which not only traps the key in its operating position until the transmitting mechanism is fully wound but also forces the key I00 out of engagement with the driving mechanism as the restoration signal is being transmitted. This feature of the invention makes it possible for the station operator to detect the stoppage of the mechanism during a restoration signal and prevents attempts to defeat the mechanism by applying force through the key at the time an alarm condition exists, as it is obvious that the key can not engage the driving mechanism once the mechanism is in its normal fully wound condition. Furthermore, the key trapping mechanism simplifies the winding operation in that it compels a certain definite sequence of operations and only those operations whereby an amateur can wind the transmitter.

Another advantage derived from this invention arises from the fact that different diaphragms of the type usually used in aero tube systems have slightly different characteristics, and therefore by providing the particular tripping mechanism disclosed herein together with the adjustable yoke which supports the tripping mechanism it is possible to adjust the tension on the two diaphragms to such a degree that they perform substantially alike. Furthermore, this particular form of trip mechanism provides a single adjustment of both diaphragms.

The particular trip mechanism also makes it possible to manually operate the transmitter by means of a simple manual trip.

It is not intended that the tripping mechanism operated by the aero tube system shall be limited only to use in signal transmitters as it is equally adaptable for use in connection with automatically operated valves in fire extinguishing sprinkler systems where such valves are of the type adapted to be opened by a tripping mechanism. It is also intended that this mechanism embodying the invention disclosed herein may be adaptable to trip any form of device wherein a trip mechanism is useful and necessary. Further advantages and modifications of this invention will be apparent to those skilled in the art, and therefore it is desired that this invention not be limited to the specific mechanical elements shown herein but only as required by the prior art and the appended claims. The winding mechanism described and illustrated herein constitutes the subject matter of my copending divisional application Serial No. 453.509, filed August 4, 1942, Patent No. 2,343,964, granted March 14, 1944.

I claim:

1. In combination, a mechanical tripping mechanism, a signal transmitter controlled by said tripping mechanism comprising a motor, an impulse wheel driven by said motor, a governing, fan driven by said motor and engaged with said tripping mechanism whereby release of said fan starts said motor, a notched main cam driven by said motor, a manually operable arm in engagement with said tripping mechanism for releasing it, a pin in said operating arm and in engagement with the notch in said cam whereby movement of the cam operates said operating arm and said tripping mechanism to positively release said fan, a. secondary cam on the drive shaft of said motor, a connection between said main cam and said secondary cam whereby said main cam rotates said secondary cam, means in positive connection with said motor, a pin in said secondary cam, a rotatable stop lever having an operating arm positioned for engagement with the pin insaid secondary cam, a lug on said stop lever positioned to engage said means to interrupt operation of said motor and a second lug on said stop lever positioned to engage said first mentioned arm to prevent engagement of the pin in said arm with the main cam.

2. In combination, a, tripping mechanism, a signal transmitter controlled by said tripping mechanism comprising a motor, rotating means driven by said motor and normally engaged with said tripping mechanism, a notched main cam driven by said motor, a manually operable arm connected with said tripping mechanism, a pin in said arm and normally in engagement with the notch in said cam whereby movement of the cam operates said arm and said tripping mechanism to positively release said fan, a secondary cam floating on the drive shaft of said motor, a lost motion connection between said main cam and said secondary cam whereby said main cam may rotate in excess of 360 with respect to said secondary cam, a pin in said secondary cam, a rotatable stop lever having an operating arm positioned for engage- V ment with the pin in said secondary cam, a lug on said stop lever positioned to engage a portion of said motor to interrupt its operation and a second lug on said stop lever positioned to engage said first mentioned arm to prevent engagement of the pin in said arm with the main cam,

3. In combination, a tripping device, a motor controlled by said tripping device, means driven by said motor and engaged with said tripping device whereby release of said means starts said motor, a main cam driven by said motor, a manually operable arm connected to release said tripping device, a follower connected to said arm and in engagement with said cam whereby movement of the cam operates said arm and said tripping device to positively release said motor, a rotatable stop lever having an arm, means connected with said main cam for engaging said arm, a lug on said stop lever positioned to engage a portion of said motor to interrupt its operation and a second lug on said stop lever positioned to engage said first arm to prevent engagement of the follower with the main cam.

4. In combination, a signal transmitter comprising a tripping mechanism, a motor, means driven by said motor and engaged with said tripping mechanism whereby release of said means starts said motor, a main cam driven by said motor, an operating arm connected to operate said tripping mechanism, a pin follower on said operating arm operable to tively release said fan, a secondary cam floating on the drive shaft of said motor, a lost motion connection between said main cam and said secondary cam whereby said main cam may rotate in eXcess of 360 with respect to said secondary cam, a pin in said secondary cam, a stop lever having an operatin arm positioned for engagement with the pin in said secondary cam, a lug on said stop lever positioned to engage a portion of said motor to interrupt its operation and a, second lug on said stop lever positioned to engage said first mentioned operating arm to prevent engagement of the follower in said arm with the main cam.

6. In combination, a mechanical tripping mechanism, a signal transmitter controlled by said tripping mechanism comprising a motor, a governing fan driven by said motor and associated with said tripping mechanism whereby release of said fan starts said motor, a cam driven by said motor, an operating arm which'is manually operable to release said tripping mechanism, a pin connected to said operating arm and in engagement with said cam whereby movement of the cam operates said operating arm and said tripping mechanism to positively release said fan and an impulse wheel driven by said motor for transmitting distinctive signals.

'7. In combination, a tripping mechanism, a signal transmitter controlled by said tripping mechanism comprising a motor, means driven by said motor and associated with said tripping mechanism whereby release of said means starts said motor, a cam driven by said motor, an operating arm linked with said tripping mechanism,

'" a follower connected tosaid operating arm and in engagement with said cam whereby movement of the cam operates said operating arm and said tripping mechanism to positively release said drivenmeans, and an impulse wheel driven by said motor for transmitting distinctive signals.

8. In combination, a mechanical tripping mechanism, a motor controlled by said tripping mechanism, means driven by said motor and associated with said tripping mechanism whereby release of said means starts said motor, an oprelease said tripping mechanism, and means driven by said motor for moving said operating arm and said tripping erating arm and in engagement with said cam whereby movement of the cam operates said operating arm and said tripping mechanism to positively release said motor, and a stop means having a portion controlled by the main cam and other portions for engaging a portionof said motor to interrupt its operation and for engagingsaid operating arm to prevent engagement of the fol lower on said operating arm with the main cam.

5. In combination, a mechanical tripping mechanism, a motor controlled by said tripping mechanism, a governing fan driven by said motor and engaged with said tripping mechanism whereby release of said fan starts said motor, a main cam driven by said motor, an operating arm engageable with and manually operable to release said tripping mechanism, a follower connected to said operating arm and in engagement with said cam whereby movement of the cam operates said operating arm and said tripping mechanism to posimechanism to positively release said first driven means.

9. In combination, a mechanical tripping mechanism operative in a vertical plane, a signal transmitter controlled by said tripping mechanism comprising a spring driven motor, a governing fan driven by said motor and engaged with mechanism whereby vertical motion said tripping of said linkage releases said fan and starts said motor, said fan having a slotted portion, and a manually operable linkage connected to said mechanical tripping mechanism for engaging and moving said mechanical tripping mechanism in a horizontal plane into alignment with the slotted portion of said fan'to release said fan and spring driven motor.

10. In combination, a tripping mechanism operative in a vertical plane, a device controlled by said tripping mechanism comprising a slotted member engaged with said tripping mechanism whereby release of said member releases said device, and a manually operable linkage connected to said tripping mechanism for engaging and moving said tripping mechanism in a horizontal plane into alignment with the slot in said member to release said device.

FRANCIS C. EVANS. 

